This revised application of ROIHS1028. Of the two modes of coronary reperfusion for acute myocardial infraction (AMI), thrombolytic therapy (TT) can be given by any emergency department physician, whereas emergency percutaneous transluminal coronary agioplasty (PTCA) requires a trained interventional cardiologist in a specialized center, as PTCA may be more effective than TT. Needed is a controlled "effectiveness trail" of AMI outcomes treated at range of hospitals in the U.S. to test what role these treatments should have. This would include random assignment in the field by EMS to the local community hospital or to a cardiac center. Because time is crucial determinant of outcome regardless of reperfusioin mode, to ethically perform such a trial there must be a method to determine instantly in the field the maximum allowable transport delay for PTCA for a given patient. Based on the outcome models for treatment of AMI with TT in our Thrombolytic Predictive Instrument (TPI), and the TPI electrocardiograph randomization program used for our TPI Clinical Trail (R01HS08212) , we propose to revise our TPI models to include PTCA treatments, and to incorporate them into an enhanced TPI electrocardiograph. This would provide to on-site EMS staff a computed length of transport delay permissible without nullifying the potential incremental benefit of PTCA for a given patient, the upper limit of the "time interval of mathematical equipoise" (TIME). If transport time to the PTCA center were within that TIME, then randomization would be appropriate. In addition to being key for running such a trail, the enhanced TPI could be useful as a clinical decision aid for treatment of patients with AMI, and for policy analyses for cardiac services. Thus, our aims are: 1. To create mathematical models that allow delineation of the TIME during which referral to a cardiac center for potential PTCA is justified; 2. To explore the clinical and policy implications, and the concept of TIME, in the choice of treatments and hospitals types; 3. Based on the TPI electrocardiograph, incorporate the outcome models for TT and PTCA into this instrument. These approaches can substantially impact the care of patients with AMI, the most common cause of death and largest consumer of health care resources in this country.